Store-operated Ca2+ entry is exaggerated in fresh preglomerular vascular smooth muscle cells of SHR
Store-operated Ca2+ entry is exaggerated in fresh preglomerular vascular smooth muscle cells of SHR
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DOI：
10.1046/j.1523-1755.2002.00383.x
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发表时间：
2002-06-01
影响因子：
19.6
通讯作者：
Arendshorst, WJ
中科院分区：
文献类型：
--
作者：
Fellner, SK;Arendshorst, WJ
背景。肾小球前血管舒缩血管的调节最终控制肾小球滤过率、钠重吸收和全身血压。为了深入了解可能导致高血压的复杂肾脏血流动力学因素，我们研究了钙信号通路。方法。利用磁化微球/筛分技术从 5 至 6 周龄的 SHR 和 WKY 中分离出新鲜的单个肾小球前血管平滑肌细胞 (VSMC)。使用 fura-2 比率荧光测量胞质 Ca2+ ([Ca2+ ](i) )。为了检查存储操作的钙进入（SOC），在含有硝苯地平的无钙缓冲液中激活 VSMC。为了消耗肌浆网 (SR) 的 Ca2+，加压素-1 受体激动剂 [V-1 R；使用肌醇三磷酸（IP3）介导的动员]、兰尼碱（非IP3诱导的动员）和环匹阿尼酸（CPA；Ca2+-ATP酶抑制）。添加外部钙，然后用 Mn2+ 猝灭 fura/Ca2+ 信号，允许通过 SOC. 结果评估二价阳离子的进入。与 WKY 相比，V-1 R 在 SHR 中引起更大的动员（P < 0.01）以及更多的钙进入（P < 0.001）。 Ryanodine 和 CPA 都会导致 SR 钙消耗，这在菌株之间没有统计学差异，但在任一操作后，通过 SOC 的绝对钙进入量是 SHR 的两倍多 (P < 0.001)。 2-氨基乙氧基联苯硼烷 (2-APB) 不仅是 IP3 受体的抑制剂，也是 SOC 的抑制剂，在兰尼定和 CPA 实验中，独立于 IP3 之外，可阻止钙进入。此外，Gd3+（SOC 的选择性抑制剂）可抑制 Ca2+ 反应。我们还研究了 V-1 R 刺激的 L 通道钙进入。SHR 中的总钙反应更大，硝苯地平的绝对抑制也是如此。作为总反应的百分比，两种大鼠品系中对硝苯地平敏感的 L 型通道的参与率约为 45%。结论。利用三种不同的机制来消耗 Ca2+ 的 SR 以激活 SOC，我们首次表明，年轻 SHR 的肾小球前 VSMC 中 SOC 被夸大。
Background. Regulation of preglomerular vasomotor tone vessels ultimately control glomerular filtration rate, sodium reabsorption and systemic blood pressure. To gain insight into the complex renal hemodynamic factors that may result in hypertension, we studied calcium signaling pathways.Methods. Fresh, single, preglomerular vascular smooth muscle cells (VSMC) were isolated from 5- to 6-week-old SHR and WKY utilizing a magnetized microsphere/sieving technique. Cytosolic Ca2+ ([Ca2+ ](i) ) was measured with fura-2 ratiometric fluorescence. To examine store-operated calcium entry (SOC), VSMC were activated in calcium-free buffer containing nifedipine. To deplete the sarcoplasmic reticulum (SR) of Ca2+ , vasopressin-1 receptor agonist [V-1 R; inositol trisphosphate (IP3 )-mediated mobilization], ryanodine (non-IP3 induced mobilization), and cyclopiazonic acid (CPA; Ca2+ -ATPase inhibition) were utilized. Addition of external calcium followed by quenching of the fura/Ca2+ signal with Mn2+ permitted assessment of divalent cation entry via SOC.Results. V-1 R caused greater mobilization in SHR than WKY (P < 0.01) as well as greater calcium entry (P < 0.001). Ryanodine and CPA both caused SR calcium depletion that was not statistically different between strains, but absolute calcium entry through SOC was more than double in SHR following either maneuver (P < 0.001). 2-Amino-ethoxybiphenyl borane (2-APB), an inhibitor not only of IP3 receptors, but also of SOC, blocked calcium entry in the ryanodine and CPA experiments independent of IP3 . As well, Gd3+ , a selective inhibitor of SOC, inhibited the Ca2+ response. We also studied L-channel calcium entry stimulated by V-1 R. The total calcium response was greater in SHR as was the absolute inhibition by nifedipine. As a percent of the total response, participation of L-type channels sensitive to nifedipine was about 45% in both strains of rat.Conclusion. Utilizing three separate mechanisms to deplete the SR of Ca2+ in order to activate SOC, we show for the first time, that SOC is exaggerated in preglomerular VSMC of young SHR.